The following article was published in The Conversation.
Explainer: what is stomach flu?
By Michael Tam
Nausea, vomiting, tummy pain and cramps, watery diarrhoea … We’ve all had acute gastroenteritis at some stage.
As a general practitioner, my patients usually refer to their condition in more colloquial terms – “gastro”, “the runs”, “the trots”, “stomach flu”, as well as other colourful names that are too indecent to publish.
Gastroenteritis is usually an infection of the gastrointestinal tract and can be caused by many different organisms:
- viruses (such as norovirus, enterovirus, and rotavirus),
- bacteria (such as E. coli and Campylobacter), and
- parasites (such as giardia).
In Australia, acute gastroenteritis is most commonly due to viruses, and is typically mild. Although it is not usually dangerous, it can be severe and even life-threatening in rare cases.
Australian readers may be aware of norovirus, which has had some recent notoriety in the news. Earlier this month, it was responsible for 26 passengers vomiting and having diarrhoea on a flight from Chile to Sydney.
It is also worth mentioning rotavirus, which is a contemporary public health triumph. Rotavirus is one of the leading causes of severe gastroenteritis in children aged under five and responsible for half a million deaths a year – mainly in low-income countries.
In Australia, it was previously responsible for more than 10,000 hospitalisations each year. But since the introduction of the oral rotavirus vaccine into the national immunisation program in 2007, there’s been a sustained reduction in hospitalisation due to this organism by over 70%.
Bacterial and parasitic causes of gastroenteritis are uncommon in Australia, except in the case of returned travellers. Traveller’s diarrhoea is frequently the result of an infection with one of the strains of E. coli that release toxins that affect the bowel.
Like gastroenteritis, traveller’s diarrhoea is also known by a range of popular names, generally in keeping with the exotic locale where disaster struck. We have “Montezuma’s revenge”, “Bali belly”, the “Rangoon runs”, and the “Hong Kong dog” among others.
Where did it come from?
On the theme of the use of vernacular slang for diarrhoeal diseases, one of interesting changes that I have noticed as an Australian GP is use of the term “stomach flu” for gastroenteritis. Reflecting back, I don’t think any of my patients used this label even a few years ago.
The fantastic Google Trends tool seems to bear out my (unscientific) observation. As far as Google is concerned, the first occurrence of “search interest” for the term “stomach flu” in Australia was in August 2008 (Figure 1).
There have been subsequent spikes of interest in the winters of 2009 to 2013, which is consistent with the fact that outbreaks of viral gastroenteritis tend to occur in the colder months.
In fact, the British call norovirus by the descriptive (and rather unimaginative) moniker “winter vomiting disease”.
We see different search statistics for the United States (Figure 2) where the term “stomach flu” is used much more frequently. There are consistent search interest spikes for “stomach flu” in winter months of the northern hemisphere all the way back to 2004, the earliest available data.
The community shift in calling gastroenteritis “stomach flu” in Australia has come with some confusion; some of my patients recently asked whether the “flu vaccine” would protect them against “stomach flu”!
What influenza is (and isn’t)
Although many viruses can cause acute gastroenteritis, influenza, the virus that is responsible for “flu” is not one of them.
Influenza is a respiratory disease, not a gastrointestinal one. Although people suffering from influenza may experience nausea, vomiting and diarrhoea, they are rarely the main symptoms.
Common symptoms of the flu include fever, sweats, body aches, lethargy and coughs. Influenza immunisation is not effective against contracting gastroenteritis – even in the slightest.
For the most part, acute gastroenteritis is a self-limiting disease. It usually resolves completely without medical treatment.
Most people simply require some rest and plenty of fluids. Oral rehydration solutions, which contain a specific mix of sugar and salts, can be useful in recovering from dehydration and are available from community pharmacies.
But gastroenteritis is contagious, so scrupulous hand hygiene is important to prevent transmission. Other simple preventive strategies include not preparing food for others, and avoiding child care, school or work for at least 48 hours after diarrhoea or vomiting stops.
As always, if you are unsure or have questions about your health, you should seek the assistance of your regular general practitioner.
Michael Tam is a community general practitioner and sees patients suffering from gastroenteritis.